We studied symmetric and asymmetric InGaAsP-InGaAs 1.55-μm multiquantum-well (MQW) laser diodes (LDs) with highly p-doped layers in the two-step separate confinement heterostructure (SCH). The p-doping in p-SCH suppresses the electron overflow from the MQWs to p-SCH, but it is an origin of free carrier absorption loss. An additional InGaAsP layer inserted inside n-SCH makes asymmetric field distribution and, therefore, reduces the portion of optical field distribution in highly p-doped regions with high optical loss. Compared with symmetric structure, asymmetric SCH LD has low threshold current density, low internal loss, and high and flat slope efficiency with respect to temperature.
Bibliographical noteFunding Information:
Manuscript received January 9, 2004; revised April 3, 2004. This work is supported in part by the Korean Ministry of Science and Technology through the National Research Laboratory (NRL). D. Heo, I. K. Han, and J. I. Lee are with the Nano Device Research Center, Korea Institute of Science and Technology, Seoul 130-650, Korea (e-mail: firstname.lastname@example.org). J. Jeong is with the Department of Radio Communications Engineering, Korea University, Seoul 136-701, Korea. Digital Object Identifier 10.1109/LPT.2004.829772 Fig. 1. (a) Schematic band structure of InGaAs–InGaAsP–InP MQW active layer with two-step SCH (confining–bounding) layer. (b) Doping concentration-depth profile of the structures.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Electrical and Electronic Engineering